The desirability of transferring liquid from one container to another without the necessity of, or ability to, pour the liquid from the first container in to the second container has long been known. Prior apparatus for accomplishing this transfer of fluid have utilized a differential in the air pressure between the respective containers to accomplish this transfer. Either the pressure was reduced in the receiving container, i.e., a partial vacuum was created, or the pressure in the dispensing container was increased above that in the receiving container. In either instance, fluid flowed from the higher pressure container into the lower pressure container.
One type of device already known in the art connects the fluid receiving container to the fluid dispensing container by means of a hose or conduit. The receiving container is tightly sealed and a vacuum pump connected to the receiving container reduces the air pressure within the container. Due to the reduction of pressure within the receiving container, the fluid in the dispensing container, which is subjected to atmospheric pressure is caused to flow through the hose or conduit into the receiving container, thereby effecting fluid transfer. Devices of this type are commercially available. One such device is sold by Neward Enterprises, under the trademark "Mityvac". These prior devices have suffered from an inability to satisfactorily transfer viscous fluids, such as motor oil or heavy transmission fluid, caused by an improper seal around the hose or conduit in the fluid receiving chamber and the minimal projected cross-sectional area of fluid tube exposed to either vacuum or pressure.
An alternate type of device presently utilized for the transfer of fluids is a squeeze bottle. In this type of device, pressure is exerted on a flexible bottle or container reducing the volume of the container, which thereby increases the air pressure within the container which, in turn, forces fluid within the container out through a hose or nozzle which is exposed to the now-lower atmospheric pressure. This type of prior device has also suffered from an inability to maintain a proper seal about the hose or nozzle when using a larger projected cross-sectional area of fluid tube exposed to either vacuum or pressure, which results in a reduced liquid transfer rate.
A need, therefore, exists for a cap or lid for liquid transfer containers which will provide a sufficient seal to maintain a vacuum or pressure differential sufficient to transfer viscous fluids under a vacuum or other fluids under pressure.